In recent years, with the rapid development of military combat technology worldwide, research on target detection and identification has deepened, integrating polarization characteristics with the intensity information of plumes to enhance the detection and identification performance of aerial targets from multiple dimensions. This article studies the spatial distribution characteristics of ultraviolet polarized radiation in gas-solid two-phase flow plumes through the improved Spherical Harmonic Discrete Ordinate Method (SHDOM). Adjustments were made to SHDOM to suit the complex environment of plumes, and the spatial distribution cloud diagram of Stokes parameters in solid rocket motor plumes was analyzed through simulation. Simulation results indicate that the overall spatial distribution of polarized radiation components in two-phase flow plumes is similar, but the positions of the internal peaks differ; the detection zenith angle directly impacts the distribution characteristics of polarized radiation in the plume, with all polarized radiation components in the plume increasing as the detection angle increases. These improvements and studies deepen the understanding of the polarization radiation characteristics of vehicle plumes, providing an important theoretical basis for enhancing the precision of plume detection and analysis.
KEYWORDS: Ultraviolet radiation, Chemical reactions, Vibration, Data modeling, Chemical analysis, Ionization, Chemistry, Performance modeling, Thermodynamics, Temperature distribution
The primary purpose of this research is to analyze the impact of different chemical reaction models on the characteristics of NO ultraviolet spectral radiation in the shock layer of hypersonic vehicles. The study is conducted from two main aspects. Firstly, three different non-equilibrium chemical reaction models—Gupta, Park, and the modified Ozawa model—were used to simulate the non-equilibrium flow field in the shock layer of the vehicle. Secondly, we further analyzed the effects of different chemical reaction models on the formation of substances in the shock layer and the characteristics of NO ultraviolet spectral radiation. In this paper, we conducted an in-depth study and analysis using the typical flight case of the BSUV (Bow-shock Ultraviolet) flight experiment, which revealed that the non-equilibrium chemical reaction models in the shock layer significantly influence the concentration and distribution of substances, thereby affecting the ultraviolet spectral radiation. By comparing the computational results with the experimental detection spectra, the Park model showed better agreement with the experimental data, with a weighted error below 10%, outperforming the Gupta chemical reaction model. The Park model exhibits comprehensive performance in the current computational cases.
The study of hypersonic aircraft and their tail flames is an important area of research in the field of aerodynamics. The tail flame of such aircraft is an important characteristic, as it affects the aerodynamic stability of the aircraft and has implications for the safety and efficiency of flight. In order to accurately simulate the tail flame and calculate its spectral radiation characteristics, it is necessary to analyze the scattering characteristics of the ablative particles in detail. This involves studying the changes in optical properties that occur as a result of variations in the proportion of mixed ablation products, specifically B2O3 and SiO2, during the early stages of the reaction. The paper under consideration focuses on the analysis of this process, with particular attention given to the properties of the new modified material ZrB2-SiC. The researchers used MIE scattering theory combined with independent scattering approximation to compare and analyze the process. Their findings indicate that the extinction coefficient decreases with the increase of ablation time during this early transition stage, while the difference in scattering image function is not significant. Therefore, it is suggested that the difference of scattering phase function can be ignored in future studies. The phase function of SiO2 particles is directly taken as the final result. This study is of great significance for the development of more accurate simulation models of flame in the tail of hypersonic aircraft, as it emphasizes the need for a detailed understanding of the scattering properties of ablative particles. By analyzing the optical properties of these particles, we can better understand the situation of tail flame and predict its spectral radiation characteristics more accurately. This information can be used to improve the safety and efficiency of hypersonic aircraft and may have wider applications in the field of aerodynamics.
Based on atmospheric background radiation, the radiation transfer equation is derived and solved by discrete coordinate method. The atmospheric background radiance and atmospheric transmittance are calculated in visible light, short-wave infrared and near-infrared bands (0.4 to 2.5μm) under space-based satellite detection and ground-based observation modes respectively, and the influence of cloud distribution on atmospheric background radiance is summarized and analyzed. The results show that the influence of clouds on atmospheric transmittance is related to zenith Angle under ground-based detection conditions, and the influence of cirrus clouds on atmospheric transmittance increases gradually with the increase of zenith Angle under most bands.
The infrared radiation characteristics of aircraft engine plume are of great significance for aircraft detection and identification. At present, with the requirements of engine combustion chamber environment, some new coating materials came into being. This material will produce a large number of gaseous and solid ablation particles in the reaction process, so the emission and scattering of ablation particles must be considered in the calculation of plume infrared radiation transfer. Based on the refractive index data of ZrO2 particles given in the literature, the scattering phase function, scattering cross section, albedo and asymmetry factor of ZrO2 particles are calculated by T matrix. The scattering phase function of ablative particles at different wavelengths and the change of scattering characteristics of ablative particles with the passage of reaction time are analyzed. The results show that the scattering effect is obvious when the wavelength is short. With the increase of combustion time, the forward scattering of clusters increases sharply, and the scattering at all angles is more obvious. Therefore, it is necessary to accurately calculate the scattering characteristics of ablation particles in order to accurately calculate the radiation characteristics of aircraft plume in the future.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.